Solve the following expression and give your answer as a fraction. $ -20\% \times 0.4 \times \dfrac{7}{10} = {?} $
Solution: First get all of the numbers as simplified fractions. $ -20\% = -\dfrac{20}{100} = -\dfrac{1}{5} $ $ 0.4 = \dfrac{4}{10} = \dfrac{2}{5} $ Now we have: $ -\dfrac{1}{5} \times \dfrac{2}{5} \times \dfrac{7}{10} = {?} $ $ \phantom{ -\dfrac{1}{5} \times \dfrac{2}{5} \times \dfrac{7}{10}} = \dfrac{-1 \times 2 \times 7} {5 \times 5 \times 10} $ $ \phantom{ -\dfrac{1}{5} \times \dfrac{2}{5} \times \dfrac{7}{10}} = -\dfrac{14}{250} = -\dfrac{7}{125} $